Abstract Understanding brain function and developing therapies for neurological conditions requires an ability to manipulate specific cell types non-invasively. The Chalasani lab has been developing a new technology using low-frequency ultrasound to activate neurons engineered to express mechanosensitive channels (?sonogenetics?). They have validated this approach in the nematode C. elegans and have obtained preliminary data demonstrating its efficacy in rodents. This proposal is aimed at identifying additional ultrasound-sensitive ion channels that are activated by different intensities and/or frequencies of ultrasound. Preliminary studies conducted at the Marine Biological Laboratories identified five aquatic invertebrates (hydra, hydroid, barnacle, octopus, and squid) that exhibit behavioral responses to ultrasound without microbubbles, which are typically used to amplify the ultrasound stimulus. For instance, the colonial cnidarian hydroid (Hydractinia) responded to a single 10-ms pulse of ultrasound (1.06?2.22 MPa peak negative pressure) by withdrawing its polyps. Using publicly available sequencing data, the Edsinger lab obtained full-length sequence for the mechanosensory TRP channel from this Hydractinia species. The Chalasani lab then synthesized the corresponding gene and showed that it can be used to confer ultrasound responsiveness to mammalian cells both in vitro (assessed via calcium indicators and electrophysiology) and in vivo (assessed using a feeding-behavior assay in mice). Success of this pipeline motivates the two laboratories to analyze mechanosensory channel sequences (TRP-Ns, Piezo, DEG/ENaC, and K2P) from the four other ultrasound-responsive species. The Edsinger lab will use either public information, next generation sequencing data, or single-molecule long-read sequencing data to identify the homologs of these mechanosensory proteins from the ultrasound-responsive species (Aim 1). The Chalasani lab will synthesize these genes and test their ability to confer ultrasound sensitivity to HEK293 cells, to mammalian neurons in vitro, and to neurons that regulate feeding behavior in vivo in mice (Aim 2). These studies will expand the sonogenetics toolbox, identifying channels that are sensitive to a range of ultrasound intensities in a microbubble-independent manner. Such a toolbox is vital for adapting this technology for use in a range of species, including humans.